Asynchronous reductant insertion in aftertreatment systems

ABSTRACT

An aftertreatment system comprises a first SCR system, a second SCR system positioned downstream of the SCR system and a reductant storage tank. At least one reductant insertion assembly is fluidly coupled to the reductant storage tank. The at least one reductant insertion assembly is also fluidly coupled to the first SCR system and the SCR system. A controller is communicatively coupled to the reductant insertion assembly. The controller is configured to instruct the reductant insertion assembly to asynchronously insert the reductant into the first SCR system and the second SCR system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional of U.S. patent application Ser.No. 14/848,685 filed Sep. 9, 2015, the contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to aftertreatment systems foruse with internal combustion (IC) engines.

BACKGROUND

Exhaust aftertreatment systems are used to receive and treat exhaust gasgenerated by IC engines. Conventional exhaust gas aftertreatment systemsinclude any of several different components to reduce the levels ofharmful exhaust emissions present in exhaust gas. For example, certainexhaust aftertreatment systems for diesel-powered IC engines include aselective catalytic reduction (SCR) system to convert NO_(X) (NO and NO₂in some fraction) into harmless nitrogen gas (N₂) and water vapor (H₂O)in the presence of ammonia (NH₃). Generally in such conventionalaftertreatment systems, an exhaust reductant, (e.g., a diesel exhaustfluid such as urea) is injected into the aftertreatment system toprovide a source of ammonia, and mixed with the exhaust gas to partiallyreduce the NO_(X) gases. The reduction byproducts of the exhaust gas arethen fluidically communicated to the catalyst included in the SCRaftertreatment system to decompose substantially all of the NO_(X) gasesinto relatively harmless byproducts which are expelled out of suchconventional SCR aftertreatment systems.

An exhaust reductant is generally inserted into the SCR system as thesource of ammonia to facilitate the reduction of constituents such asNO_(X) gases of the exhaust gas (e.g., a diesel exhaust gas). Theexhaust reductant is stored in a reductant storage tank and communicatedto the SCR system. The reductant generally includes an aqueous solutionsuch as an aqueous urea solution. Reductant insertion assemblies aregenerally used to deliver the reductant from the reductant storage tank.Multiple SCR systems can be included in an aftertreatment system and thereductant has to be delivered to each of the multiple SCR systems atabout the same time to prevent any degradation in the catalyticconversion efficiency of each of the multiple SCR systems.

SUMMARY

Embodiments described herein relate generally to systems and methods ofdelivering reductant to multiple SCR systems included in anaftertreatment system and, in particular, to a reductant insertionassembly and method for asynchronously delivering reductant from asingle reductant storage tank to an upstream and a downstream SCRsystem.

In a first set of embodiments, an aftertreatment system comprises afirst SCR system, a second SCR system positioned downstream of the SCRsystem and a reductant storage tank. At least one reductant insertionassembly is fluidly coupled to the reductant storage tank. The at leastone reductant insertion assembly is also fluidly coupled to the firstSCR system and the second SCR system. A controller is communicativelycoupled to the reductant insertion assembly. The controller isconfigured to instruct the reductant insertion assembly toasynchronously insert the reductant into the first SCR system and thesecond SCR system.

In another set of embodiments, a system for asynchronously deliveringreductant from a reductant storage tank to a first SCR system and asecond SCR system included in an aftertreatment system comprises areductant insertion assembly fluidly coupled to the reductant storagetank. The reductant insertion assembly is also fluidly coupled to eachof the first SCR system and the second SCR system. A control module iscommunicatively coupled to the reductant insertion assembly. The controlmodule comprises a controller configured to instruct the reductantinsertion assembly to asynchronously insert the reductant into the firstSCR system and the second SCR system.

In yet another set of embodiments, a method for asynchronouslydelivering a reductant to a first SCR and a second SCR system of anaftertreatment system via a reductant insertion assembly which includesa first injector fluidly coupled to the first SCR and a second injectorfluidly coupled to the second SCR system comprises activating the firstinjector. The first injector is maintained activated for a firstdelivery time, thereby inserting a first amount of reductant into thefirst SCR system. The first injector is deactivated. The second injectoris activated. The second injector is maintained activated for a seconddelivery time, thereby inserting a second amount of reductant into thesecond SCR system.

In still another set of embodiments, a control module comprises acontroller configured to be communicatively coupled to a reductantinsertion assembly of an aftertreatment system. The aftertreatmentsystem includes a first SCR system and a second SCR system. Thereductant insertion assembly includes a first injector fluidly coupledto the first SCR system, and a second injector fluidly coupled to thesecond SCR system. The controller includes a timing determination moduleconfigured to determine a first activation time at which the firstinjector is to be activated and a first delivery time for which thefirst injector is to be selectively activated for delivering a firstamount of reductant into the first SCR system. The timing determinationmodule is also configured to determine a second activation time at whichthe second injector is to be activated, and a second delivery time forwhich the second injector is to be selectively activated for deliveringa second amount of reductant into the second SCR system. A firstinsertion module is configured to activate the first injector at thefirst activation time for the first delivery time, thereby deliveringthe first amount of reductant to the first SCR system. A secondinsertion module is configured to activate the second injector at thesecond activation time for the second delivery time, thereby deliveringthe second amount of reductant to the second SCR system. The firstactivation time is different from the second activation time.

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the inventive subject matter disclosed herein. In particular, allcombinations of claimed subject matter appearing at the end of thisdisclosure are contemplated as being part of the inventive subjectmatter disclosed herein.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several implementations in accordance withthe disclosure and are therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

FIG. 1 is a schematic illustration of an aftertreatment system,according to an embodiment.

FIG. 2 is an illustration of another embodiment of an aftertreatmentsystem.

FIG. 3 is a schematic block diagram of a control module that can beincluded in the aftertreatment system of FIG. 1 and/or FIG. 2.

FIG. 4 is a plot of current vs time showing activation of an exampleinjector showing various phases of fluid flow during an activation cycleof the injector.

FIG. 5 is a timing diagram showing the time points at which thereductant is inserted into the first SCR system and the second SCRsystem of FIGS. 1 and/or 2, and the activation duration of a firstinjector (injector 1) configured to insert the reductant into the firstSCR system, and the activation duration of the second injector (injector2) configured to insert the reductant into the second SCR system.

FIG. 6 is a schematic flow diagram of another embodiment of a method ofinserting a reductant into a first SCR system and a second SCR system ofan aftertreatment system via a reductant insertion assembly fluidlycoupled to each of the first SCR system and the second SCR system.

FIG. 7 is a schematic block diagram of an embodiment of a computingdevice which can be used as a controller included in the aftertreatmentsystems of FIG. 1 or FIG. 2.

Reference is made to the accompanying drawings throughout the followingdetailed description. In the drawings, similar symbols typicallyidentify similar components, unless context dictates otherwise. Theillustrative implementations described in the detailed description,drawings, and claims are not meant to be limiting. Other implementationsmay be utilized, and other changes may be made, without departing fromthe spirit or scope of the subject matter presented here. It will bereadily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, and designed in a wide variety ofdifferent configurations, all of which are explicitly contemplated andmade part of this disclosure.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Embodiments described herein relate generally to systems and methods ofdelivering reductant to multiple SCR systems included in anaftertreatment system, and in particular, to a reductant insertionassembly and method for asynchronously delivering reductant from asingle reductant storage tank to an upstream and a downstream SCRsystem.

Aftertreatment systems can include multiple SCR systems. It is desirableto deliver reductant to each of the multiple SCR systems at the sametime or approximately the same time (e.g., less than a second apart) toprevent any degradation in the catalytic conversion of any one of theSCR systems due to lag in delivering of the reductant thereto. Whilemultiple reductant insertion assemblies and/or reductant storage tankscan be used to deliver the reductant to each of the multiple SCRsystems, this can complicate the assembly of such aftertreatment systemsas well as raise assembly and/or maintenance costs.

Various embodiments of the systems and methods described herein fordelivering reductant to a first SCR system and a second SCR systemincluded in an aftertreatment system may provide benefits include, forexample (1) providing reductant to the first SCR system and the secondSCR system from a single reductant storage tank; (2) using a reductantinsertion assembly which includes a first injector dedicated to deliverreductant only to the first SCR system and a second injector dedicatedto delivering reductant only to the second SCR system from a single pumpincluded in the reductant insertion assembly; (3) asynchronouslyactivating the first injector and the second injector so that reductantis delivered to the first SCR system and the second SCR systemsequentially; and (4) activating the first injector and the secondinjector for a very short period of time, e.g., less than 10milliseconds, so that the reductant is delivered near simultaneously tothe first SCR system and the second SCR system, for example within 10milliseconds of each other.

FIG. 1 is a schematic illustration of an aftertreatment system 100,according to an embodiment. The aftertreatment system 100 is configuredto receive an exhaust gas (e.g., a diesel exhaust gas) from an engine(e.g., a diesel engine) and reduce constituents of the exhaust gas suchas, for example, NO_(X) gases, CO, etc. The aftertreatment system 100includes a reductant storage tank 110 (also referred to herein as “tank110”), a reductant insertion assembly 120, a first SCR system 140, asecond SCR system 150 and a controller 170.

The tank 110 contains an exhaust reductant formulated to facilitatereduction of the constituents of the exhaust gas (e.g., NO_(X)) by acatalyst included in the first SCR system 140 and the second SCR system150. In embodiments in which the exhaust gas is a diesel exhaust gas,the exhaust reductant can include a diesel exhaust fluid (DEF) whichprovides a source of ammonia. Suitable DEFs can include urea, aqueoussolution of urea or any other DEF (e.g., the DEF available under thetradename ADBLUE®).

The first SCR system 140 is positioned upstream of the second SCR system150. In other embodiments, the first SCR system 140 and the second SCRsystem 150 can be positioned in a parallel arrangement. For example, thefirst SCR system 140 can be positioned on a first bank or leg of theaftertreatment system 100, and the second SCR system 150 can bepositioned on a second bank or leg of the aftertreatment system 100which is parallel to the first bank or leg.

Each of the first SCR system 140 and the second SCR system 150 areconfigured to receive and treat the exhaust gas (e.g., a diesel exhaustgas) flowing through each of the first SCR system 140 and the second SCRsystem 150. Each of the first SCR system 140 and the second SCR system150 are fluidly coupled to the tank 110 to receive the reductanttherefrom via the reductant insertion assembly 120, as described herein.In various embodiments, the first SCR system 140 can include a SCR onfilter. In such embodiments, the first SCR system 140 is configured todecompose constituents of the exhaust gas as well as filter particulatematter (e.g., soot, carbon, dust, etc.) from the exhaust gas.

Each of the first SCR system 140 and the second SCR system 150 includeat least one catalyst positioned within an internal volume defined by ahousing of each of the first SCR system 140 and the second SCR system150. The catalyst is formulated to selectively reduce constituents ofthe exhaust gas, for example NO_(X) included in the exhaust gas in thepresence of an exhaust reductant. Any suitable catalyst can be used suchas, for example, platinum, palladium, rhodium, cerium, iron, manganese,copper, vanadium based catalysts (including combinations thereof).

The catalyst can be disposed on a suitable substrate such as, forexample, a ceramic (e.g., cordierite) or metallic (e.g., kanthal)monolith core which can, for example, define a honeycomb structure. Awashcoat can also be used as a carrier material for the catalyst. Suchwashcoat materials can include, for example, aluminum oxide, titaniumdioxide, silicon dioxide, any other suitable washcoat material, or acombination thereof. The exhaust gas can flow over and about thecatalyst such that any NO_(X) gases included in the exhaust gas arefurther reduced to yield an exhaust gas which is substantially free ofcarbon monoxide and NO_(X) gases.

The reductant insertion assembly 120 is fluidly coupled to the tank 110and each of the first SCR system 140 and the second SCR system 150, andis configured to insert the reductant into each of the first SCR system140 and the second SCR system 150 from the tank 110, as describedherein. The reductant insertion assembly 120 includes a first injector123 fluidly coupled to the first SCR system 140 and configured to insertthe reductant into the first SCR system 140. In various embodiments, afirst mixer (not shown) can be positioned upstream of the first SCRsystem 140. In such embodiments, the first injector 123 is fluidlycoupled to the first mixer and is configured to insert the reductantinto the first mixer upstream of the first SCR system 140.

The reductant insertion assembly 120 also includes a second injector 125fluidly coupled to the second SCR system 150 and configured to insertthe reductant into the second SCR system 150. In various embodiments, asecond mixer (not shown) may be positioned upstream of the second SCRsystem 150 and downstream of the first SCR system 140. In suchembodiments, the second injector 125 is fluidly coupled to the secondmixer and configured to insert the reductant into the second mixerupstream of the second SCR system 150.

Each of the first injector 123 and the second injector 125 can includeany suitable injector or injection assembly for inserting apredetermined amount of reductant into the first SCR system 140 and thesecond SCR system 150, respectively. Each of the first injector 123 andthe second injector 125 can include valves (e.g., a solenoid valve, aplate valve, a diaphragm valve or any other suitable valve), nozzles,conduits or any other suitable components or otherwise injector forperforming the insertion of the reductant into the first SCR system 140and the second SCR system 150, respectively. In particular embodiments,the reductant insertion assembly 120 may also include a pump (notshown). The pump is fluidly coupled to each of the first injector 123and the second injector 125 and configured to selectively deliver thereductant from the tank 110 to each of the first injector 123 and thesecond injector 125 at a predetermined pressure. The pump can include acentrifugal pump, a diaphragm pump, a valve pump, a screw pump or anyother suitable pump.

The controller 170 is communicatively coupled to the reductant insertionassembly 120. The controller 170 is configured to instruct the reductantinsertion assembly 120 to asynchronously insert the reductant into thefirst SCR system 140 and the second SCR system 150. The asynchronouslyinserting includes selectively inserting the reductant only into thefirst SCR system 140 or only into the second SCR system 150 at any giventime. In other words, the reductant is either inserted into the firstSCR system 140 or the second SCR system 150 at any given time but notboth.

For example, the controller 170 can be communicatively coupled to thefirst injector 123 and the second injector 125. The controller 170 isconfigured to activate the first injector 123, thereby initiatinginsertion of the reductant into the first SCR system 140. The controller170 maintains the first injector 123 activated for a first delivery timefor inserting a first amount of reductant into the first SCR system 140.The controller 170 deactivates the first injector 123, thereby stoppingthe insertion of the reductant into the first SCR system 140.

The controller 170 then activates the second injector 125, therebyinitiating insertion of the reductant into the second SCR system 150.The controller 170 maintains the second injector activated for a seconddelivery time for inserting a second amount of reductant into the secondSCR system 150. The controller 170 can then deactivate the secondinjector 125 and reactivate the first injector 123 to insert thereductant into the first SCR system 140. In this manner, the controller170 sequentially activates the first injector 123 and the secondinjector 125 to sequentially insert the reductant into the first SCRsystem 140 and the second SCR system 150. The sequential insertion isrepeated to allow asynchronous delivery of the reductant to each of thefirst SCR system 140 and the second SCR system 150.

In various embodiments, each of the first delivery time and the seconddelivery time can be sufficiently small so that the reductant isdelivered almost simultaneously to each of the first SCR system 140 andthe second SCR system 150. For example, each of the first delivery timeand the second delivery time can be less than 10 milliseconds (e.g., 9,8, 7, 6 or 5 milliseconds). The chemical kinetics involved in thecatalytic conversion of constituents of the exhaust gas by the catalystof the first SCR system 140 and the second SCR system 150 is a slowprocess (e.g., occurring over several second).

In contrast, the asynchronous activation of the first injector 123 andthe second injector 125 is a rapid process having a less than 10millisecond lag between activation of the first injector 123 and thesecond injector 125. Therefore, although the reductant is insertedasynchronously into the first SCR system 140 and the second SCR system150, the first delivery time and the second delivery time issufficiently small (e.g., less than 10 milliseconds) so that there is nonegative impact on the performance of either the first SCR system 140 orthe second SCR system 150. In various embodiments, the first deliverytime is equal to the second delivery time so that the first amount ofreductant inserted into the first SCR system 140 is equal to the secondamount of reductant inserted into the second SCR system 150.

Although not shown in FIG. 1, the aftertreatment system 100 can includesensors such as, for example, temperature sensors, pressure sensors,NO_(X) sensors, oxygen sensors, ammonia sensors and/or any othersensors. The controller 170 may be communicatively coupled to one ormore such sensors to receive and interpret signals from one or more ofthese sensors. The controller 170 may use the information from one ormore of these sensors to determine, for example, the first or secondactivation time and/or the first or second delivery time.

The controller 170 can include a processor (e.g., a microcontroller)programmed to interpret the output signal. In some embodiments, thecontroller 170 can be included in a control module (e.g., the controlmodule 271 described herein) which is in electrical communication withone or more of the components of the aftertreatment system 100 describedherein and operable to perform the sensing and control functionsdescribed herein. In particular embodiments, the controller 170 can alsobe configured to receive and interpret data from, temperature sensors,NO_(X) sensors, oxygen sensors and/or ammonia sensors, each of which canbe included in the aftertreatment system 100, as described before.

FIG. 2 shows another embodiment of an aftertreatment system 200. Theaftertreatment system 200 includes a reductant storage tank 210, areductant insertion assembly 220, a first oxidation catalyst 230, afirst mixer 238, a first SCR system 240, a second mixer 248, a secondSCR system 250, a second oxidation catalyst 252 and a controller 270.The aftertreatment system 200 is configured to receive an exhaust gasfrom an engine 20 and decompose constituents (e.g., NO_(X) gas includedin the exhaust gas) and includes a housing within which each of thefirst oxidation catalyst 230, the first mixer 238, the first SCR system240, the second mixer 248, the second SCR system 250 and the secondoxidation catalyst 252 are positioned.

The engine 20 includes an IC engine which can include a diesel engine, agasoline engine, a natural gas engine, a biofuel (e.g., biodiesel)engine or a dual-fuel (e.g., diesel and natural gas) engine. The engine20 produces the exhaust gas which is delivered to the aftertreatmentsystem 200 for decomposing constituents (e.g., NO_(X) gases) included inthe exhaust gas. An exhaust gas recirculation (EGR) system 24 can befluidly coupled to the engine 20 and configured to recirculate a portionof the exhaust gas generated by the engine to upstream of the engine,for example to reduce a combustion temperature of the fuel in one ormore combustion chamber of the engine 20. A charge air cooler 22 canalso be fluidly coupled to an intake of the engine 20 and configured tocool the intake air provide to the engine 20, for example after the airhas passed through a turbocharger 26 positioned upstream of the firstoxidation catalyst 230.

The reductant storage tank 210 (also referred to herein as the “tank210”) contains a reductant, for example a diesel exhaust fluid. Thereductant facilitates decomposition of the constituents (e.g., NO_(X)gases) of the exhaust gas. The tank 210 can be substantially similar tothe tank 110 described with respect the aftertreatment system 100, andtherefore not described in further detail herein.

The first oxidation catalyst 230 is positioned upstream of the firstmixer 238. In various embodiments, the first oxidation catalyst 230 caninclude a diesel oxidation catalyst configured to reduce CO and unburnthydrocarbons included in the exhaust gas. A first NO_(X) sensor 227 anda first temperature sensor 229 are positioned upstream of the firstoxidation catalyst 230 and configured to measure an amount of NO_(X) inthe exhaust gas as well as a temperature of the exhaust gas upstream ofthe first oxidation catalyst 230.

A second NO_(X) sensor 231 and a second temperature 237 are positioneddownstream of the first oxidation catalyst 230 and configured to measurean amount of NO_(X) in the exhaust gas as well as a temperature of theexhaust gas upstream of the first oxidation catalyst 230. The firstmixer 238 is positioned downstream of the first oxidation catalyst 230.The first mixer 238 in configured to receive the reductant and theexhaust gas and include vanes, passages, turbulence generators or anyother suitable structures configured to facilitate mixing of thereductant with the exhaust gas.

The first SCR system 240 is positioned downstream of the first mixer 238and is configured to decompose constituents of the exhaust gas. Invarious embodiments, the first SCR system 240 can include an SCR onfilter, configured to catalytically decompose constituents (e.g., NO_(X)gases included in the exhaust gas) as well as filter particulate matterincluded in the exhaust gas. The first SCR system 240 is substantiallysimilar to the first SCR system 140 included in the aftertreatmentsystem 100 and therefore not described in further detail herein. Adifferential pressure sensor 241 is positioned across the first SCRsystem 240 and configured to measure a pressure difference across thefirst SCR system 240. The pressure difference corresponds to a pressuredrop across the first SCR system 240 which is indicative of the amountof particular matter trapped in the first SCR system 240. This can beused to determine if the first SCR system 240 (e.g., a SCR on filter) isplugged with particulate matter and thereby, a performance of the firstSCR system 240.

A third temperature sensor 243 and an ammonia sensor 245 is positioneddownstream of the first SCR system 240 and configured to determine atemperature of the exhaust gas downstream of the first SCR system 240and an amount of ammonia in the exhaust gas downstream of the first SCRsystem 240.

The second mixer 248 is positioned downstream of the first SCR system240. A fourth temperature sensor 247 is positioned proximate to theinlet of the second mixer 248 to determine a temperature of the exhaustgas entering the second mixer 248. The second SCR system 250 ispositioned downstream of the second mixer 248 and configured to reduceconstituents (e.g., NO_(X) gases) included in the exhaust gas. Thesecond SCR system 250 can be substantially similar to the second SCRsystem 150 included in the first aftertreatment system 100 describedbefore, and therefore not described in further detail herein.

The second oxidation catalyst 252 is positioned downstream of the secondSCR system 250. In various embodiments, the second oxidation catalyst252 includes an ammonia oxidation catalyst or an ammonia slip catalyst.The ammonia oxidation catalyst is configured to decompose unconsumedammonia included in the exhaust gas exiting the second SCR system 250which is released due to decomposition of a reductant (e.g., an aqueousurea solution) in the first SCR system 240 and/or the second SCR system250. A fifth temperature sensor 251, a third NO_(X) sensor 253 and aparticulate matter sensor 255 are positioned downstream of the secondoxidation catalyst 252 and configured to measure a temperature of theexhaust gas, amount of NO_(X) in the exhaust gas and amount ofparticulate matter entrained in the exhaust gas downstream of the secondoxidation catalyst 252, respectively.

The reductant insertion assembly 220 is fluidly coupled to the tank 210and configured to deliver the reductant to each of the first SCR system240 and the second SCR system 250. As shown in FIG. 2, the reductantinsertion assembly 220 includes a pump 222 fluidly coupled to the tank210. The pump 222 can include a centrifugal pump, a diaphragm pump, avalve pump, a screw pump or any other suitable pump.

The reductant insertion assembly 220 also includes a first injector 223and a second injector 225. The first injector 223 is fluidly coupled tothe first mixer 238 and configured to insert the reductant into thefirst mixer 238 upstream of the first SCR system 240 to allow thereductant to be efficiently mixed with the exhaust gas before theexhaust gas enters the first SCR system 240. The second injector 225 isfluidly coupled to the second mixer 248 and configured to insert thereductant into the second mixer 248 upstream of the second SCR system250 to allow the reductant to be efficiently mixed with the exhaust gasbefore the exhaust gas enters the second SCR system 250.

The pump 222 is fluidly coupled to each of the first injector 223 andthe second injector 225 and configured to deliver the reductant from thetank 210 to the first injector 223 and the second injector 225 at apredetermined pressure.

The controller 270 is communicatively coupled to the reductant insertionassembly 220 and more specifically, to each of the pump 222, the firstinjector 223 and the second injector 225. The controller 270 can besubstantially similar to the controller 170 included in theaftertreatment system 100. In various embodiments, the aftertreatmentsystem 200 includes a control module which includes the controller 270and is communicatively coupled to the reductant insertion assembly 220.For example, FIG. 3 is a schematic block diagram of a control module 271that includes the controller 270 according to an embodiment. Thecontroller 270 can be includes a processor 272, a memory 274 or othercomputer readable medium, a sensor 276 and a transceiver 278. It shouldbe understood that the controller 270 shows only one embodiment of thecontroller 270 and any other controller capable of performing theoperations described herein can be used (e.g., the computing device630).

The controller 270 is configured to instruct the reductant insertionassembly 220 to asynchronously insert the reductant into the first SCRsystem 240 and the second SCR system 250. The asynchronously insertingincludes inserting the reductant only into the first SCR system 240 oronly into the second SCR system 250 at any given time. In variousembodiments, the sensor 276 can include an electrical sensor configuredto receive and interpret one or more engine operating parameter (e.g.,an engine on/off condition, engine load, engine lean/rich condition,etc.) The engine operating parameters can be used to determine an amountof reductant, a pressure at which the reductant is to be delivered,and/or a delivery time of the reductant to be delivered by the firstinjector 223 and the second injector 225 into the first SCR system 240and the second SCR system 250, respectively.

The processor 272 can include a microprocessor, programmable logiccontroller (PLC) chip, an ASIC chip, or any other suitable processor.The processor 272 is in communication with the memory 274 and configuredto execute instructions, algorithms, commands or otherwise programsstored in the memory 274.

The memory 274 includes any of the memory and/or storage componentsdiscussed herein. For example, memory 274 may include RAM and/or cacheof processor 272. Memory 274 may also include one or more storagedevices (e.g., hard drives, flash drives, computer readable media, etc.)either local or remote to device controller 270. The memory 274 isconfigured to store look up tables, algorithms or instructions.

For example, the memory 274 includes a timing determination module 274a. The timing determination module 274 a is configured to determine afirst activation time at which the first injector 223 is to be activatedand a first delivery time for which the first injector 223 is to bemaintained opened for delivering a first amount of reductant into thefirst SCR system 240 (i.e., into the first mixer 238 positioned upstreamof the first SCR system 240. The timing determination module 274 a isalso configured to determine a second activation time at which thesecond injector 225 is to be activated, and a second delivery time forwhich the second injector 225 is to be maintained opened for deliveringa second amount of reductant into the second SCR system 250 (i.e., intothe second mixer 248 positioned upstream of the second SCR system 250).In various embodiments, the timing determination module 274 a isconfigured to interpret one or more engine operating parameters todetermine at least one of the first activation time, the first deliverytime, the second activation time and/or the second delivery time.

Moreover, the memory 274 also includes a first insertion module 274 band a second insertion module 274 c. The first insertion module 274 b isconfigured to activate the first injector 223 at the first activationtime for the first delivery time, thereby delivering the first amount ofreductant into the first SCR system 240. Similarly, the second insertionmodule 274 c is configured to activate the second injector 225 at thesecond activation time for the second delivery time, thereby deliveringthe second amount of reductant into the second SCR system 250.

The controller 270 also includes a transceiver 278 configured togenerate a first insertion signal for activating the first injector 223and a second insertion signal for activating the second injector 225,respectively. The first insertion signal and/or the second insertionsignal can include a voltage, a current or any other electrical signalcommunicated to the first injector 223 and the second injector 225,respectively to perform the activation.

The first and second insertion signal is maintained for the first andsecond delivery time to deliver the first and second amount of reductantto the first SCR system 240 and the second SCR system 250, respectively.The first activation time is different from the second activation time,for example the second activation time occurs immediately after thefirst delivery time so that the reductant is asynchronously delivered tothe first SCR system 240 and the second SCR system 250 as describedbefore herein.

For example, FIG. 4 is a plot an activation profile of an exampleinjector which can be used as the first injector 223 and/or the secondinjector 225. The plot shows current on the Y-axis corresponding to asignal current (e.g., generated by the transceiver 278) for activatingthe injector and the X-axis corresponds to the time. There is no flowthrough the injector until the injector is opened at the activationtime. As the injector is activated, there is dynamic flow through theinjector as the injector opens (e.g., a valve of the injector opens) andthe reductant is drawn into the injector. This is referred to as thepull in time in FIG. 4.

The reductant is then inserted into the aftertreatment component (e.g.,the first SCR system 240 or the second SCR system 250) from the injectorwhich is referred to as the hold time in FIG. 4. The flow through theinjector is static once the injector is completely opened. Finally, theinjector is deactivated which involves a small time of dynamic flow asthe injector is closing until the injector completely closes and theflow completely stops. The sum of the pull in time, the hold time andthe closing time define the delivery time (e.g., the first and/or thesecond delivery time) during which a predetermined amount of reductant(e.g., the first amount or the second amount) of reductant is deliveredinto the SCR system.

FIG. 4 shows the delivery time to be 5 milliseconds. In other exampleembodiments, the delivery time can be less than 10 milliseconds (e.g.,5, 6, 7, 8 or 9 milliseconds inclusive of all ranges and valuestherebetween). FIG. 5 is a plot of a timing diagram of a first injector(injector 1) and a second injector (injector 2) which include theinjector of FIG. 4 and can be used as the first injector 123 or 223 andthe second injector 125 or 225, respectively. The timing diagram isconfigured to asynchronously deliver the reductant to a first SCR system(e.g., the first SCR system 140 or 240) and a second SCR system (e.g.,the second SCR system 150 or 250).

As shown in FIG. 5 the first injector is activated at the firstactivation time (0 milliseconds). The first injector is maintained inthe activated positioned for a first delivery time of 5 milliseconds todeliver a first amount of reductant to the first SCR system. The firstinjector is then deactivated. As soon as the first injector completelydeactivates or closes as described with reference to FIG. 4, the secondinjector is activated. The second injector is maintained in theactivated positioned for the second delivery time, to deliver a secondamount of reductant to the second SCR system.

The second delivery time is the same as the first delivery time i.e., 5milliseconds. Therefore an equal amount of reductant is insertedasynchronously into the first SCR system and the second SCR system. Inother embodiments, the first delivery time can be different from thesecond delivery time. As described before, the first delivery time andthe second delivery are sufficiently small so that the reductant isdelivered near simultaneously to each of the first SCR system and thesecond SCR system, thereby having minimal or no impact on theperformance of each of the first SCR system and the second SCR system,as described before herein.

FIG. 6 is a schematic flow diagram of an example method 400 ofasynchronously delivering a reductant to a first SCR system (e.g., thefirst SCR system 140 or 240) and a second SCR system (e.g., the secondSCR system 150 or 250) included in an aftertreatment system (e.g., theaftertreatment system 100 or 200) using a reductant insertion assembly(e.g., the reductant insertion assembly 120 or 220) fluidly coupled tothe aftertreatment system. The reductant insertion assembly includes afirst injector (e.g., the first injector 123 or 223) fluidly coupled tothe first SCR system, and a second injector (e.g., the second injector125 or 225) fluidly coupled to the second SCR system. The operations ofthe method 400 can be stored in the form of instructions on anon-transitory CRM (e.g., the memory 274 of the controller 270, or mainmemory 636, read only memory (ROM) 638 or storage device 640 included inthe computing device 630 of FIG. 7). The CRM can be included in acomputing device (e.g., the computing device 630) which is configured toexecute the instructions stored on the CRM to perform the operations ofthe method 400.

The method 400 includes activating a first injector at 402. For example,the first insertion module 274 b of the controller 270 activates thefirst injector 223 at a first activation time by sending a signal to thefirst injector 223 via the transceiver 278. The first injector ismaintained activated for a first delivery time, thereby inserting afirst amount of reductant into the first SCR system at 404. For example,the first insertion module 274 b can provide the activation signal tothe first injector 223 for the first delivery time to maintain the firstinjector in the activated or open position for the first delivery time.In various embodiments, the first delivery time is less than 10milliseconds (e.g., 5, 6, 7, 8 or 9 milliseconds inclusive of all rangesand values therebetween).

The first injector is deactivated at 406. For example, the firstinsertion module 274 b instructs the transceiver to stop thecommunication of the activation signal to the first injector 223 todeactivate the first injector 223. The second injector is activated at408. For example, the second insertion module 274 c of the controller270 instructs the transceiver 278 to communicate an activation signal tothe second injector 225 at a second activation time to activate thesecond injector 225. The second activation time occurs immediately afterthe first delivery time is over, as described before herein.

The second injector is maintained in the activated position for a seconddelivery time, thereby inserting a second amount of reductant into thesecond SCR system at 410. For example, the second insertion module 274 ccan provide the activation signal to the second injector 225 for thesecond delivery time to maintain the second injector in the activated oropen for the second delivery time. The second delivery time can also beless than 10 milliseconds (e.g., 5, 6, 7, 8 or 9 milliseconds inclusiveof all ranges and values therebetween). In various embodiments, thesecond delivery time is equal to the first delivery time (e.g., 5milliseconds). Furthermore, the first amount of reductant inserted intothe first SCR system can be the same as the second amount of reductantinserted into the second SCR system. The second injector is deactivatedat 412. The method than returns to operation 402 and the insertionoperations are repeated.

In some embodiments, the controller 170, 270 or any of the controllersdescribed herein can comprise a system computer of an apparatus orsystem which includes the aftertreatment system 100 or 200 (e.g., avehicle, an engine or generator set, etc.). For example, FIG. 7 is ablock diagram of a computing device 630 in accordance with anillustrative implementation. The computing device 630 can be used toperform any of the methods or the processes described herein, forexample the method 400. In some embodiments, the controller 170 or 270can include the computing device 630. The computing device 630 includesa bus 632 or other communication component for communicatinginformation. The computing device 630 can also include one or moreprocessors 634 or processing circuits coupled to the bus for processinginformation.

The computing device 630 also includes main memory 636, such as a randomaccess memory (RAM) or other dynamic storage device, coupled to the bus632 for storing information, and instructions to be executed by theprocessor 634. Main memory 636 can also be used for storing positioninformation, temporary variables, or other intermediate informationduring execution of instructions by the processor 634. The computingdevice 630 may further include ROM 638 or other static storage devicecoupled to the bus 632 for storing static information and instructionsfor the processor 634. A storage device 640, such as a solid-statedevice, magnetic disk or optical disk, is coupled to the bus 632 forpersistently storing information and instructions. For exampleinstructions for determining the first activation time, the firstdelivery time, the second insertion time and the second delivery timecan be stored in the storage device.

The computing device 630 may be coupled via the bus 632 to a display635, such as a liquid crystal display, or active matrix display, fordisplaying information to a user. An input device 642, such as akeyboard or alphanumeric pad, may be coupled to the bus 632 forcommunicating information and command selections to the processor 634.In another implementation, the input device 642 has a touch screendisplay 644.

According to various implementations, the processes and methodsdescribed herein can be implemented by the computing device 630 inresponse to the processor 634 executing an arrangement of instructionscontained in main memory 636 (e.g., the operations of the method 400).Such instructions can be read into main memory 636 from anothernon-transitory computer-readable medium, such as the storage device 640.Execution of the arrangement of instructions contained in main memory 36causes the computing device 730 to perform the illustrative processesdescribed herein. One or more processors in a multi-processingarrangement may also be employed to execute the instructions containedin main memory 636. In alternative implementations, hard-wired circuitrymay be used in place of or in combination with software instructions toeffect illustrative implementations. Thus, implementations are notlimited to any specific combination of hardware circuitry and software.

Although an example computing device has been described in FIG. 7,implementations described in this specification can be implemented inother types of digital electronic circuitry, or in computer software,firmware, or hardware, including the structures disclosed in thisspecification and their structural equivalents, or in combinations ofone or more of them.

Implementations described in this specification can be implemented indigital electronic circuitry, or in computer software, firmware, orhardware, including the structures disclosed in this specification andtheir structural equivalents, or in combinations of one or more of them.The implementations described in this specification can be implementedas one or more computer programs, i.e., one or more modules of computerprogram instructions, encoded on one or more computer storage media forexecution by, or to control the operation of, data processing apparatus.Alternatively or in addition, the program instructions can be encoded onan artificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially-generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate components or media (e.g., multiple CDs, disks, or otherstorage devices). Accordingly, the computer storage medium is bothtangible and non-transitory.

The operations described in this specification can be performed by adata processing apparatus on data stored on one or morecomputer-readable storage devices or received from other sources. Theterm “data processing apparatus” or “computing device” encompasses allkinds of apparatus, devices, and machines for processing data, includingby way of example a programmable processor, a computer, a system on achip, or multiple ones, or combinations of the foregoing. The apparatuscan include special purpose logic circuitry, e.g., an FPGA (fieldprogrammable gate array) or an ASIC (application-specific integratedcircuit). The apparatus can also include, in addition to hardware, codethat creates an execution environment for the computer program inquestion, e.g., code that constitutes processor firmware, a protocolstack, a database management system, an operating system, across-platform runtime environment, a virtual machine, or a combinationof one or more of them. The apparatus and execution environment canrealize various different computing model infrastructures, such as webservices, distributed computing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for performing actions in accordance with instructions andone or more memory devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom or transfer data to, or both, one or more mass storage devices forstoring data, e.g., magnetic, magneto-optical disks, or optical disks.However, a computer need not have such devices. Devices suitable forstoring computer program instructions and data include all forms ofnon-volatile memory, media and memory devices, including by way ofexample semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices; magnetic disks, e.g., internal hard disks or removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry.

It should be noted that the term “example” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” and the like as used herein mean the joining of twomembers directly or indirectly to one another. Such joining may bestationary (e.g., permanent) or moveable (e.g., removable orreleasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

It is important to note that the construction and arrangement of thevarious exemplary embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein.Additionally, it should be understood that features from one embodimentdisclosed herein may be combined with features of other embodimentsdisclosed herein as one of ordinary skill in the art would understand.Other substitutions, modifications, changes and omissions may also bemade in the design, operating conditions and arrangement of the variousexemplary embodiments without departing from the scope of the presentinvention.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features described in this specification in thecontext of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresdescribed in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

What is claimed is:
 1. A system for asynchronously delivering reductantfrom a reductant storage tank to a first selective catalytic reductionsystem and a second selective catalytic reduction system included in anaftertreatment system, comprising: a reductant insertion assemblyfluidly coupled to the reductant storage tank, the reductant insertionassembly configured to be fluidly coupled to each of the first selectivecatalytic reduction system and the second selective catalytic reductionsystem; and a control module communicatively coupled to the reductantinsertion assembly, the control module comprising: a controllerconfigured to: instruct the reductant insertion assembly toasynchronously insert the reductant into the first selective catalyticreduction system and the second selective catalytic reduction system. 2.The system of claim 1, wherein the asynchronously inserting includesinserting the reductant only into the first selective catalyticreduction system or only into the second selective catalytic reductionsystem at any given time.
 3. The system of claim 1, wherein thereductant insertion assembly includes: a first injector fluidly coupledto the first selective catalytic reduction system; and a second injectorfluidly coupled to the second selective catalytic reduction system. 4.The system of claim 3, wherein the controller is further configured to:activate the first injector; maintain the first injector activated for afirst delivery time to insert a first amount of reductant into the firstselective catalytic reduction system; deactivate the first injector;activate the second injector; and maintain the second injector activatedfor a second delivery time to insert a second amount of reductant intothe second selective catalytic reduction system.
 5. The system of claim4, wherein the first delivery time is equal to the second delivery time.6. The aftertreatment system of claim 5, wherein the first amount isequal to the second amount.
 7. The aftertreatment system of claim 4,wherein the reductant insertion assembly further includes: a pumpfluidly coupled to each of the first injector and the second injector,the pump delivering the reductant from the reductant storage tank toeach of the first injector and the second injector at a predeterminedpressure.
 8. The aftertreatment system of claim 7, wherein each of thefirst injector and the second injector include a valve.
 9. Theaftertreatment system of claim 1, wherein the second selective catalyticreduction system is positioned downstream of the first selectivecatalytic reduction system.
 10. A method for asynchronously delivering areductant to a first selective catalytic reduction and a secondselective catalytic reduction system of an aftertreatment system via areductant insertion assembly, the reductant insertion assemblycomprising a first injector fluidly coupled to the first selectivecatalytic reduction and a second injector fluidly coupled to the secondselective catalytic reduction system, the method comprising: activatingthe first injector; maintaining the first injector activated for a firstdelivery time, thereby inserting a first amount of reductant into thefirst selective catalytic reduction system; deactivating the firstinjector; activating the second injector; and maintaining the secondinjector activated for a second delivery time, thereby inserting asecond amount of reductant into the second selective catalytic reductionsystem.
 11. The method of claim 10, wherein the first delivery time isequal to the second delivery time.
 12. The method of claim 10, whereinthe first amount is equal to the second amount.
 13. A control modulecomprising: a controller configured to be communicatively coupled to areductant insertion assembly of an aftertreatment system, theaftertreatment system including a first selective catalytic reductionsystem and a second selective catalytic system, the reductant insertionassembly including a first injector fluidly coupled to the firstselective catalytic reduction system, and a second injector fluidlycoupled to the second selective catalytic reduction system, thecontroller including: a timing determination module configured todetermine: a first activation time at which the first injector is to beactivated, a first delivery time for which the first injector is to beselectively activated for delivering a first amount of reductant intothe first selective catalytic reduction system, a second activation timeat which the second injector is to be activated, and a second deliverytime for which the second injector is to be selectively activated fordelivering a second amount of reductant into the second selectivecatalytic reduction system; a first insertion module configured toactivate the first injector at the first activation time for the firstdelivery time, thereby delivering the first amount of reductant into thefirst selective catalytic reduction system; and a second insertionmodule configured to activate the second injector at the secondactivation time for the second delivery time, thereby delivering thesecond amount of reductant into the second selective catalytic reductionsystem, wherein the first activation time is different from the secondactivation time.
 14. The control module of claim 13, wherein the secondactivation time occurs immediately after the first amount of reductanthas been delivered to the first selective catalytic reduction system.15. The method of claim 13, wherein the first delivery time is equal tothe second delivery time.